The present invention relates to the measurement of picture quality in a digital video system, and more particularly to a picture quality monitoring system for measuring picture quality at all layers in a television program chain.
Because conventional methods for assessing picture quality of a video sequence assume a linear system, they are not effective in testing compressed video systems, which are nonlinear. Thus alternate methods are needed. One such method is picture differencing, such as is described in allowed U.S. Pat. No. 5,818,520 issued Oct. 6, 1998 by Bozidar Janko and David Fibush entitled "Programmable Instrument for Automatic Measurement of Compressed Video Quality." Here a test video sequence is passed through the system under test and then compared with the original version of the test video sequence using the Sarnoff JNDMetrix technology. However such a system gives an overall metric for the entire system, while not identifying the portion of the system that represents the greatest degradation.
What is desired is a picture quality monitoring system that applies the difference test to all layers in a television program chain--video, compression and RF.